Generally, the present invention relates to services provided by an intelligent network. More specifically, the invention relates to call forwarding services implemented by means of an intelligent network.
A telecommunications network that includes facilities for providing various services and attributes is called an Intelligent Network (IN). It is an architecture built on the existing telecommunications network, and one of its most important features is its ability to segregate call switching from the service logic. The intelligent network offers the subscriber quick and flexible access to personalised services without any modifications to the software at the exchange. This is possible because the services are controlled by a few centralised control points in the intelligent network specifically designed for this purpose.
FIG. 1a shows a simplified example of the structure of the intelligent network. Let us first briefly examine the individual components of the intelligent network and the functions residing in these components.
Subscriber Equipment SE, such as a fixed-wire telephone, mobile station (MS), computer or fax machine, is connected directly to a Service Switching Point SSP.
The service switching point SSP gives the user access to the network, makes the necessary selections and offers the opportunity to use the various services available in the intelligent network. SSP performs two main functions: the Call Control Function CCF and the Service Switching Function SSF. The service switching point SSP identifies the call attempts requesting IN services. At the service switching point, the numbers requiring IN control have been defined in the service trigger table. The service switching point SSP requests instructions for routing the call and performing the service from the IN service control function SCF residing in the service control point SCP. In response, the service control point SCP sends to the service switching point SSP the physical number to which the call is routed. An ordinary call that requires no IN features is connected through the exchange in the normal fashion.
The service control point SCP is a digital exchange or dedicated computer with the necessary software. It contains the service logic, the service control functionality and the service database function. Often, the database is a Service Data Point SDP that is separate from the service control point SCP. The service control point SCP processes the service data in the database by means of its own Service Logic Program LCP and controls the service switching point SSP. Signalling between the service switching point SSP and service control point SCP is carried out via the common channel signalling network SS7 using the INAP protocol.
The service data point SDP contains the data that the service logic programs SLP use to generate personalised services. The service control point SCP can make use of the services offered by the service data point SDP.
The Intelligent Peripheral IP offers specialised services and supports flexible data communications between the user and the network. The intelligent peripheral IP features the Specialised Resource Function SRF that offers an interface to network mechanisms involved in the interaction with the user. Typical examples of such mechanisms are the announcements made to the subscriber and receiving of the subscriber selections.
The various phases of call control are modelled on the ITU-T recommendation Q.1214 by means of the Basic Call State Mode BCSM. Call set-up at the exchange consists of two processes: the originating call set-up (subscriber A) and terminating call set-up (subscriber B), the corresponding state modes being the Originating Basic Call State Mode O_BCSM and the Terminating Basic Call State Mode T_BCSM. The state mode consists of Points In Call PIC, the Detection Point DP and transitions between the various modes. The detection point can serve either as Trigger Detection Points TDP or Event Detection Points EDP. DP1 is also known as a xe2x80x9chot-line-triggerxe2x80x9d because it permits IN triggering immediately when the receiver is picked up. The TDP and EDP can be of either the Request or Notification type. If the point is of the Request type, SSP suspends call processing and asks for additional instructions from the SCP, whereas with the Notification type point, the SSP continues call processing normally, but notifies the SCP of point detection, which creates a relationship in which the SCP monitors the SSP.
FIG. 1b is a signalling diagram showing the signalling process when a connection is made between subscribers A and B (fixed-wire telephone). The SSP detects that a call is being made to subscriber B that requires IN control, in which case it sends an InitialDP signal to the SCP at point 11. The SCP responds by sending the standard RRBSCME signal at point 12, indicating the detection points to be reported, which are: DP13 meaning that subscriber B""s line is busy, DP14 meaning that subscriber B does not answer the call, DP15 meaning that subscriber B answers the call, DP17 meaning that either subscriber A or subscriber B terminates the call, and DP18 meaning that subscriber A gives up before subscriber B answers the call. At point 13, the SCP sends a Continue signal to proceed with the process. In the case used as the example, subscriber B answers the call, which is reported to the SCP by the SSP at point 14 using the EventReportBCSM signal. At point 15, the SCP responds with the Continue signal, as a result of which the call is sustained normally. In other words, a voice connection is set up between subscribers A and B and they can converse with each other.
There is a great variety of intelligent network services available and their number is increasing all the time. Here are a couple of examples of IN services: the Universal Access Number UAN, which makes it possible to call a subscriber using a single number even if he/she has dedicated telephone lines to several sites located in different areas; the Personal Number, which is independent of the network and allows the intelligent network to re-route calls made to the number involved as instructed by the subscriber; and Call Forwarding CF, where the call is transferred to another pre-defined number. The subscriber may activate the call forwarding service, for example from a fixed-wire telephone to a mobile telephone, by keying in a certain code and the mobile telephone number using the keypad of the fixed-wire telephone. Call forwarding is cancelled by keying in a pre-defined cancellation code, similarly using the keypad of the fixed-wire telephone. Call forwarding may be activated from a fixed-wire telephone at home or in the office to a mobile telephone. Once call forwarding has been activated, the fixed-wire telephone will not ring because the exchange has detected that the call forwarding service has been activated and, therefore, sends the call to the mobile telephone. It is possible, however, that the subscriber activating call forwarding is near the fixed-wire telephone (used for activating call forwarding) when the mobile telephone rings and would rather take the call on the fixed-wire telephone. At present, this is not possible.
Accordingly, the aim of the present invention is to eliminate this drawback and improve the service by making it more user-friendly as well as less expensive.
The present invention relates to intelligent network services and specifically to call forwarding, where calls are forwarded, for example, from a fixed-wire telephone to a mobile telephone.
The aim of the invention is to provide a solution that improves call forwarding services by making it more user-friendly both in terms of function and cost. This is achieved as described in the independent patent claims.
The idea of the invention is to monitor the subscriber equipment from which calls have been forwarded even after the subscriber unit to which the calls have been forwarded has been notified of the incoming call in order to see whether the user takes some pre-defined action, such as lifting the receiver. If such an action is detected, the call is re-routed to the subscriber unit from which calls have been forwarded. The service based on the invention is particularly convenient for subscribers who have both a fixed-wire line and a mobile telephone. Once the subscriber has activated call forwarding from his fixed-wire telephone to his mobile telephone, he can also take the incoming call on the fixed-wire telephone even if it is not ringing. When call forwarding has been activated and a call is about to be connected to the fixed-wire telephone (subscriber A), the SSP monitors the detection point TDP1 to determine whether the receiver of the fixed-wire telephone (subscriber B) is lifted. The re-routing process is initiated when subscriber B lifts the receiver of the fixed-wire telephone. The service control point SCP controls the call forwarding service by giving processing and routing instructions for the service switching point SSP. More precisely, the SCP activates the said xe2x80x9chot-linexe2x80x9d trigger detection point, after which it switches to the monitoring mode to supervise call forwarding, which may be direct or conditional.
The invention makes the call forwarding service less expensive because the subscriber does not have to pay for the leg used for forwarding.
Another advantage offered by the invention is that this can be implemented using the standard Capability Set 2 CS-2 features of the intelligent network.